Transvenous active fixation lead system

ABSTRACT

A medical electrical lead system that includes a catheter extending from a proximal catheter end to a distal catheter end; a lead, insertable within the catheter, including a lead body extending from a proximal lead end to a distal lead end and an active fixation member positioned at the distal lead end; and an advancement tool for advancing the distal lead end outward from the distal catheter end. The advancement tool is adapted to be positioned around the lead body and further adapted to be removably fixedly engaged with the proximal catheter end.

TECHNICAL FIELD

The invention relates generally to implantable medical devices and, inparticular, to an active fixation, transvenous lead and associateddelivery system.

BACKGROUND

Transvenous endocardial leads may be placed inside a chamber of apatient's heart by passing the lead through a venous entry site, such asthe subclavian vein or the cephalic vein, or a tributary thereof, alonga venous pathway into the superior vena cava and into the right cardiacchambers. Cardiac vein leads may be advanced further, from the rightatrium through the coronary sinus ostium into the coronary sinus andultimately into one of the various cardiac veins for stimulation and/orsensing of the left heart chambers.

Cardiac lead placement is important in achieving accurate sensing ofcardiac signals and proper cardiac stimulation pulse delivery forproviding optimal therapeutic benefit from cardiac stimulation therapiessuch as cardiac resynchronization therapy (CRT). Cardiac vein leadsgenerally need to be small in diameter to allow advancement through thecardiac veins and highly flexible in order to withstand flexing motioncaused by the beating heart without fracturing. The small diameter andflexibility of the lead, however, makes advancement of the lead along atortuous venous pathway challenging. Cardiac vein leads are generallyimplanted with the aid of a relatively stiff guide catheter and/orguidewire or stylet. Considerable skill and time are required to achieveproper placement of a transvenous lead along a cardiac vein site.

Cardiac vein leads have typically been provided with a passive fixationmember and an atraumatic tip electrode. The passive fixation memberprovides fixation of the distal lead tip by becoming lodged within anarrow cardiac vein. The distal lead tip needs to be advanced into acardiac vein that is small enough to securely lodge the lead tiptherein. Dislodgement of a passively fixed cardiac vein lead can stilloccur, however, even when the lead tip is advanced into a small vein.

The requirement of advancing the lead into a narrow cardiac vein branchfor fixation purposes imposes limitations on the possible implantlocations that may be selected. An implant site in a larger vein mayresult in more optimal sensing or stimulation in a particularindividual. Furthermore, advancement of leads deep into a small cardiacvein on the lateral free wall of the left ventricle can introduceundesired stimulation of the diaphragm during cardiac pacing.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects and features of the present invention will be appreciated as thesame becomes better understood by reference to the following detaileddescription of the embodiments of the invention when considered inconnection with the accompanying drawings, wherein:

FIG. 1 is a plan view of transvenous lead and delivery system accordingto one embodiment of the invention.

FIG. 2 is a sectional view of an advancement tool included in thedelivery system of FIG. 1.

FIG. 3 is a proximal end view of a movable member included in theadvancement tool of FIG. 2.

FIG. 4 is a plan view of one embodiment of a torque transfer member thatmay be included in the transvenous lead delivery system shown in FIG. 1.

FIG. 5 is a distal end view of the torque transfer member shown in FIG.4.

FIG. 6 is a plan view of the torque transfer member of FIG. 4 afteradvancing the stylet through a lead body.

FIG. 7 is a proximal end view of the movable member of the advancementtool of FIG. 3 assembled with the torque transfer member of FIG. 4.

FIG. 8 is a plan view of a transvenous lead assembled with a torquetransfer member and a movable member of an advancement tool.

FIG. 9 is a plan view of a transvenous lead advanced through a catheterto a cardiac vein implant site.

FIG. 10 is a plan view of an alternative embodiment of a torque transfermember.

FIG. 11 is a plan view of the torque transfer member shown in FIG. 10assembled with a lead and an advancement tool movable member.

FIG. 12 is a plan view of a lead distal end according to one embodimentof the invention.

FIG. 13 is a sectional view of a conically shaped, helically woundfixation member according to one embodiment of the invention.

DETAILED DESCRIPTION

In the following description, references are made to illustrativeembodiments for carrying out the invention. It is understood that otherembodiments may be utilized without departing from the scope of theinvention. For purposes of clarity, the same reference numbers are usedin the drawings to identify similar elements. Unless otherwise noted,drawing elements are not drawn to scale.

FIG. 1 is a plan view of transvenous lead and delivery system accordingto one embodiment of the invention. The system includes a catheter 10,an advancement tool 30, a transvenous lead 50, and a guidewire 54.Catheter 10 includes tubular elongated body 12 extending between adistal catheter end 14 and a proximal catheter end 16. A working port 24is provided at distal catheter end 14 through which guidewire 54, lead50, or other instruments or devices may be advanced outward from distalcatheter end 14. Proximal catheter end 16 is provided with a fitting 18for removably fixedly engaging advancement tool 30. An injection port 26may be provided to enable administration of contrast agents, dyes, orother fluids through catheter 10.

Elongated catheter body 12 includes a flexible distal portion 20 havinggreater flexibility than the remainder of catheter body 12. In oneembodiment, flexible distal portion 20 is tapered toward proximatedistal catheter end 14. Flexible distal portion 20 includes a distalcurve or bend 22 for directing working port 24 radially outward, at anypredetermined angle, from the central axis of catheter 10. Lead 50 (oranother instrument) advanced outward from working port 24 will bedirected in a radial direction away from the central axis of catheter10. When catheter 10 is advanced into a cardiac vein and lead 50 isadvanced outward from working port 24, lead 50 will be directed towardthe vein wall rather than along the vein lumen.

Catheter 10 may be used as a subselection catheter that is advancedthrough a larger, generally stiffer, guide catheter. During one implantprocedure for placing lead 50 in a cardiac vein location, a guidecatheter is advanced into the right atrium and the coronary sinus.Catheter 10, having lead 50 and guidewire 54 retracted therein, isadvanced through the guide catheter into the coronary sinus and furtheradvanced to a cardiac vein branch. Guidewire 54 is advanced out ofworking port 24 into the desired cardiac vein branch. Catheter 10 isadvanced over guidewire 54, into the selected cardiac vein and to atargeted implant site. The flexible distal portion 20 will trackguidewire 54 along a tortuous pathway to the implant site. Guidewire 54will act to straighten bend 22 such that distal catheter end 14 tracksguidewire 54 along the desired venous path. Guidewire 54 may be providedwith a hydrophilic coating to allow lead 50 to glide easily overguidewire 54 with minimal resistance or friction. A hydrophilic coatingmay correspond to a polysaccharide coating as generally descried in U.S.Pat. No. 5,840,046 (Deem), hereby incorporated herein by reference inits entirety.

Verification of the position of working port 24 at the targeted implantsite may be made by injection of a contrast agent through injection port26. When the working port 24 of catheter 10 is positioned at thetargeted implant site, guidewire 54 is removed. Advancement tool 30 isused to advance lead 50 outward from working port 24 to fixate thedistal lead end at the implant site, as will be described in greaterdetail herein.

Advancement tool 30 includes a movable member 34 and a fixable member32. Fixable member 32 is provided with a fitting 36 adapted for fixedlyengaging catheter fitting 18 in a removable manner. For example,advancement tool fitting 36 and catheter fitting 18 may correspond toLuer lock fittings which mate to prevent lateral or passive rotationalmovement of fixable member 32 relative to catheter 10.

Movable member 34 is adapted to move laterally with respect to fixablemember 32. In one embodiment, movable member 34 moves laterally withrespect to fixable member upon rotation of movable member 34. Fixablemember 32 includes screw-like threads 38 which mate with threads or athread guide included in movable member 34. Movable member 34 moveslaterally along fixable member 32, as indicated by arrow 35, uponrotation of movable member 34.

Movable member 34 is adapted to interface with the elongated body 56 oflead 50 to temporarily fix the position of lead 50 relative to movablemember 34. In one embodiment, movable member 34 is provided with one ormore lead engaging members embodies as set screws 40 and 42 which aretightened down to removably, fixedly engage lead 50, extending within alumen of movable member 34. In alternative embodiments, clips, springs,hinged members or other lead engaging members may be included forfixedly engaging lead 50 in a removable manner. Upon rotation of movablemember 34, lead 50 will move laterally with movable member 34 withrespect to fixable member 32 and catheter 10.

FIG. 2 is a sectional view of advancement tool 30. Advancement tool 30includes an inner surface 65 forming central lumen 66 for receiving lead50. Lumen 66 extends continuously through movable member 34 and fixablemember 32. Lead 50 is stabilized within lumen 66 by set screws 40 and42. Set screws 40 and 42 may be tightened down onto the elongated body56 of lead 50. Alternatively, lumen 66 is provided with a deformablewall 44 that becomes pressed against lead body 56 when set screws 40 and42 are tightened down toward lumen 66. Deformable wall 44 acts toprotect the lead body from being damaged by set screws 40 and 42.Deformable wall 44 is formed of a material, such as silicone rubber,that forms a non-slip or slip resistant interface with lead body 56,which is typically formed of polyurethane.

In one embodiment, movable member 34 is provided with a thread guide 60adapted to mate with threaded portion 38 of fixable member 32. Asmovable member 34 is rotated, thread guide 60 follows threaded portion38 of fixable member 32 causing lateral movement of movable member 34with respect to fixable member 32 as indicated by arrow 35. Lead 50 willbe rotated and advanced through catheter 10 as movable member 34 isrotated in a first direction, typically a clockwise direction, withrespect to fixable member 32. As will be described in greater detailherein, rotation of movable member 34 causes an active fixation memberprovided at the distal end of lead 50 to be advanced outward from thedistal working port of catheter 10 and become fixedly engaged withadjacent tissue at the implant site. Lead 50 may be retracted byrotating movable member 34 in an opposite, typically counter-clockwise,direction.

FIG. 3 is a proximal end view of movable member 34 included inadvancement tool 30. Movable member 34 is provided with across-sectional size and shape that allows an implanting clinician toreadily grip and rotate movable member 34 to facilitate advancement of alead 50 extending through advancement tool lumen 66. In the exampleshown in FIG. 3, movable member 34 is provided with a generallyoctagonal shape however movable member 34 may be provided with othercross-sectional geometries, such as generally round, square or anotherpolygonal shape. In some embodiments, movable member 34 may be providedwith ridges or other non-slip features along its exterior surface toallow the clinician to easily grip movable member 34 without slippage.Lead engaging members embodied as set screws 40 and 42 are used totemporarily fix the position of a lead extending through lumen 66relative to movable member 34. Movable member 34 includes one or moregrooves 70 and 72 adapted for receiving flanges included on a torquetransfer member as will be described below.

FIG. 4 is a plan view of one embodiment of a torque transfer member thatmay be included in the transvenous lead delivery system shown in FIG. 1.Torque transfer member 80 includes a stylet 82 extending from a flangedhandle 81. Stylet 82 extends between a distal end 84 and a proximal end85 connected to handle 81. Handle 81 is designed to interlock withmovable member 34 (shown in FIG. 3) In one embodiment, handle 81 isprovided with one or more flanges 86 and 88 which interlock with acorresponding number of grooves 70 and 72 provided in movable member 34(FIG. 3). It is recognized that numerous configurations are possible forproviding interlocking members on handle 81 and movable member 34, whichmay include flanges, pegs, rods, grooves, notches, bores, or any otherpaired interlocking structures.

Handle 81 includes a lead engaging member embodied as a set screw 87 forsecuring the position of a proximal lead connector assembly betweenflanges 86 and 88. Handle 81 further includes a receptacle 90 forreceiving and retaining the tip of a proximal lead connector pin.Receptacle 90 is sized to receive the proximal lead connector pin in asnap fit. Handle 81 may be provided as a splittable member having aperforation 83 to allow easy removal of torque transfer member 80 from alead.

FIG. 5 is a distal end view of the torque transfer member 80 shown inFIG. 4. Flanges 86 and 88 extend radially from handle 81 and areprovided with an outer dimension adapted for insertion in grooves 70 and72 of movable member 34 (FIG. 3). Stylet 82 is advanced through a leadbody until a proximal lead connector pin is securely positioned inreceptacle 90.

FIG. 6 is a plan view of torque transfer member 80 after advancingstylet 82 through a lead body 56. Lead 50 includes a proximal connectorpin 52 and an open lumen extending through lead body 56 adapted forreceiving a guidewire or stylet. Stylet 82 is advanced through lead body56 until proximal lead connector pin 52 reaches stylet proximal end 85and is received by (snapped into) receptacle 90. Stylet 82 may beprovided with a hydrophilic coating to reduce friction between lead body56 and stylet 82 and thereby promote smooth advancement of stylet 82through lead 50. Set screw 87 is tightened down on lead connector pin 52to temporarily fix stylet 82 within lead 50 in a stable manner.Receptacle 90 is sized to securely retain proximal lead connector pin52.

FIG. 7 is a proximal end view of movable member 34 assembled with torquetransfer member 80. Lead 50 is advanced through advancement tool lumen66 as shown in FIG. 2, and stylet 82 is advanced through lead 50 asshown in FIG. 6. Handle flanges 86 and 88 of torque transfer member 80are inserted into movable member grooves 70 and 72 as shown in FIG. 7.Movable member set screws 40 and 42 and torque transfer member set screw87 provide three torque transfer contact points with the lead positionedwithin advancement tool 30 and torque transfer member 80. An additionaltorque transfer contact point may be provided by including a fourth setscrew in flange 88 of torque transfer member 80. Each lead engagingmember, including set screws 40, 42, and 87 and proximal lead connectorpin receptacle 90 (shown in FIG. 6), provides a contact point fortransferring torque that is applied to rotate lead 50 during rotation ofmovable member 34.

FIG. 8 is a plan view of a transvenous lead assembled with torquetransfer member 80 and movable member 34 of advancement tool 30. Stylet82 is shown advanced through lead 50. Stylet 82 is provided with alength somewhat shorter than the length of lead body 56 such that styletdistal end 84 terminates proximal to lead distal end 92. The proximallead connector pin is removably fixedly engaged by handle 80 asdescribed above and shown in FIG. 6. Handle flange 86 is interlockedwith movable member groove 70. Likewise, handle flange 88 is interlockedwith movable member groove 72 (not visible in the view shown in FIG. 8).Set screws 40, 42, and 87 secure the position of lead 50 with respect tomovable member 34 and torque transfer member 80. Lead 50 may be packagedpre-assembled with torque transfer member 80 and/or movable member 34.Lead 50 is advanced through fixable member 32 and catheter 10. Rotationof movable member 34 causes lateral motion of lead 50 which advanceslead distal end 92 out the distal working port of catheter 10. As lead50 is advanced, active fixation member 94 provided at lead distal end 92is advanced into the tissue at a targeted implant site.

FIG. 9 is a plan view of lead 50 advanced through catheter 10 to acardiac vein implant site. During an implant procedure, catheter 10 isadvanced over a guidewire 54 (shown in FIG. 1) into a selected cardiacvein as described previously. Catheter 10, advancement tool 30, lead 50and guidewire 54 may be packaged preassembled and advanced as a singleunit through a guide catheter into the coronary sinus. Lead 50 wouldremain retracted within catheter 10 during advancement of catheter 10 toa targeted implant site. Guidewire 54 would be used to subselect adesired cardiac vein branch, and catheter 10 would track guidewire 54 toa targeted implant site. Guidewire 54 would be removed from lead 50 whenthe targeted site is reached. Stylet 82 would then be advanced throughlead 50 and torque transfer member handle 81 would be interlocked withadvancement tool 30. Movable member 34 would then be rotated to advanceactive fixation member 94 out catheter working port 24 into tissue atthe implant site. Movable member 34 is shown fully advanced onto fixablemember 32, thereby extending distal fixation member 94 a controlleddistance outward from working port 24.

Multiple torque transfer contact points provided by set screws 40, 42and 87, and lead pin connector receptacle 90 within handle 81 (shown inFIG. 6) promote efficient torque transfer from movable member 34 to lead50. Stylet 82 extending through lead body 56 adds torsional stiffness tolead body 56 and thereby promotes efficient torque transfer from themultiple torque transfer contact points along the proximal lead end tothe distal lead end 92.

Stylet distal end 84 terminates proximal to distal lead end 92 andcatheter bend 22. Fixation member 94 is directed radially outwardthrough working port 94, away from the central axis of catheter 10 andthe central lumen of cardiac vein 150. Fixation member 94 is directedinto the wall of cardiac vein 150, in the direction of the underlyingepicardial tissue 152. Distal lead end 92 can be reliably fixed in thetissue at a targeted implant site, even within a relatively largecardiac vein branch 150.

FIG. 10 is a plan view of an alternative embodiment of a torque transfermember. Torque transfer member 100 includes one or more flanges 102 and104 for interlocking with movable member 34 in the same manner asdescribed above. Torque transfer member 100 includes a central lumen 106extending between a proximal port 108 and a distal port 107 adapted forreceiving a lead body extending through lumen 106. Torque transfermember 100 includes one or more bores 114 and 116 for receivingrespective set screws 110 and 112. The base 118 of set screw bore 114and the base 120 of set screw bore 116 are formed from a deformablematerial that allows set screws 110 and 112 to be advanced securely downonto a lead body extending through lumen 106 without causing damage tothe lead body insulation. Set screw bore bases 118 and 120 are formed ofa material such as silicone rubber that provides a non-slip or slipresistant coupling with the lead body insulation, typically formed ofpolyurethane. It is recognized that other lead engaging members may beused that allow fixation of a lead within torque transfer member 100 ina removable manner, such as clips, spring elements, hinged elements,collars, or other lead engaging members.

FIG. 11 is a plan view of the torque transfer member 100 shown in FIG.10 assembled with a lead 50 and advancement tool movable member 34. Leadbody 56 extends through torque transfer member 100 and movable member34. Torque transfer member flange 102 is interlocked with movable membergroove 70. Likewise, flange 104 is interlocked with movable membergroove 72 (not visible in the view shown in FIG. 11). Set screws 40, 42,110 and 112 (shown in FIG. 10) removably, fixedly engage lead body 56with torque transfer member 100 and movable member 34 and provide torquetransfer contact points for causing rotation of lead 50 during rotationof movable member 34. The lead proximal end 96 extends outward fromproximal port 108 of torque transfer member 100. A guidewire 54 mayoptionally extend through lead 50 to provide additional support to lead50 during an implant procedure, for guiding lead 50 to an implant siteand for adding torsional resistance during lead rotation.

Torque transfer member 100 having open proximal port 108 allowsrepositioning of lead 50 within torque transfer member 100 and movablemember 34 during an implant procedure. Set screws 40, 42, 110 and 112(shown in FIG. 10) may be loosened to allow torque transfer member 100and movable member 34 to be moved along lead body 56. Repositioning oftorque transfer member 100 and movable member 34 along lead body 56 maybe needed during an implant procedure in order to advance the distal endof lead 50 a required distance outward from the working port of catheter10 to achieve fixation at a desired implant site.

FIG. 12 is a plan view of a lead distal end according to one embodimentof the invention. Lead 50 may be embodied as unipolar, bipolar, ormultipolar lead carrying one or more electrodes and/or other sensorswith corresponding conductors extending through lead body 56 to aproximal lead connector assembly at proximal lead end 96 (shown in FIG.11). Lead 50 includes distal fixation member 94 at distal lead end 92.Distal fixation member 94 is provided as an electrode that may be usedfor cardiac sensing and stimulation. As such, fixation member 94 iscoupled to a conductor extending through lead body 56 to proximalconnector pin 52 (shown in FIG. 11). In some embodiments, distalfixation member 94 may serve to fix distal lead end 92 at an implantsite without functioning as an electrode. In alternative embodiments,lead 50 may carry additional electrodes and/or sensors, each coupled tocorresponding conductors extending to respective connectors included ina proximal lead connector assembly.

Distal fixation member 94 is provided as a helix having a sharpeneddistal tip 136 for penetrating tissue at a targeted implant site. Uponrotation of lead 50 using advancement tool 30, helical fixation member94 is rotated and advanced into a targeted tissue site, thereby fixatingdistal lead end 92 at the implant site. Fixation member 94 is providedwith a generally conical shape having a narrower outer diameter neardistal tip 136 and a wider outer diameter near distal lead end 92. Thehelical windings forming fixation member 94 may be provided with aconvex leading edge 138 to form a smooth, atraumatic, conical outercontour of fixation member 94 for preventing damage to vein walls asdistal lead end 92 is advanced forward in a cardiac vein to an implantsite.

A guidewire guide 130 is provided extending from distal lead end 92,extending through one or more proximal windings of helical fixationmember 94. Guidewire guide 130 directs guidewire 54 along the centralaxis of helical fixation member 94 as guidewire 54 is advanced pastfixation member distal tip 136. The inner diameter of the distalwindings of helical fixation member 94 closely conform to the outersurface of guidewire 54 such that fixation member 94 tracks closelyalong guidewire 54.

FIG. 13 is a sectional view of a conically shaped, helically woundfixation member according to one embodiment of the invention. The innerdiameter 142 of fixation member 94 is shown to be substantially constantmoving from the distal lead body end 92 to the sharpened tip 136 offixation member 94. A wire used to from fixation member 94 would beprovided with tapering outer dimensions such that, when wound to formthe conically-shaped helix, the distal-most windings, near sharpened tip136, have a smaller cross-sectional area than the proximal-mostwindings, near distal lead body end 92. The wire would be provided witha rounded or convex geometry along the surface that becomes the leadingedge 138 of fixation member 94 as member 94 is advanced. The wire may beprovided with a relatively flat geometry on the surface that becomes theproximal-facing surface 140 of helical fixation member 94. During leadretraction, the catheter would be moved forward very close to or overfixation member 94 to protect the surrounding tissue from the fixationmember 94 as counterrotation is applied to retract the lead.

Thus, a transvenous lead and associated delivery system have beenpresented in the foregoing description with reference to specificembodiments. It is appreciated that various modifications to thereferenced embodiments may be made without departing from the scope ofthe invention as set forth in the following claims. For example, it isrecognized that the system may be used, with or without modifications,for providing a medical electrical lead implanted at other bodylocations, including endocardial locations, and is not limited tocardiac vein applications.

1. A medical electrical lead system, comprising: a catheter extendingfrom a proximal catheter end to a distal catheter end; a lead,insertable within the catheter, including a lead body extending from aproximal lead end to a distal lead end and an active fixation memberpositioned at the distal lead end; an advancement tool for advancing theactive fixation member outward from the distal catheter end, theadvancement tool being adapted to be positioned around the lead body andfurther adapted to be removably fixedly engaged with the proximalcatheter end.
 2. The system of claim 1 wherein the catheter comprises aflexible distal portion proximate the distal end.
 3. The system of claim1 wherein the catheter forms an opening at the distal catheter end and abend proximate the distal catheter end directing the opening away from acentral axis of the catheter.
 4. The system of claim 1 wherein theadvancement tool includes a fixable member adapted to be removablyfixedly engaged with the proximal catheter end and a movable memberadapted to move laterally with respect to the fixable member and furtheradapted to be removably fixedly engaged with the lead body.
 5. Thesystem of claim 4 wherein the movable member is adapted to movelaterally with respect to the fixable member upon rotation of themovable member.
 6. The system of claim 4 wherein the movable memberincludes a fixation member for removably fixedly engaging the lead body.7. The system of claim 1 further including a torque transfer memberadapted to be interlockingly engaged with the advancement tool andremovably fixedly engaged with the lead.
 8. The system of claim 7wherein the lead includes a lumen and the torque transfer memberincludes a stylet insertable within the lead lumen.
 9. The system ofclaim 7 wherein the torque transfer member includes a fixation memberfor removably fixedly engaging the lead.
 10. The system of claim 7wherein the torque transfer member includes a receptacle for receivingand retaining the proximal lead end.
 11. The system of claim 7 whereinthe torque transfer member includes a first interlocking member and theadvancement tool includes a second interlocking member adapted tointerlockingly engage the first interlocking member.
 12. The system ofclaim 1 wherein the catheter further includes a fluid injection port.13. The system of claim 1 wherein the active fixation member includes aconically shaped helix.
 14. The system of claim 13 wherein the activefixation member includes convex leading edges.
 15. The system of claim13 wherein the active fixation member includes a substantially constantinner diameter.
 16. A medical lead delivery system, comprising: meansfor directing a medical lead to a desired cardiac vein; means foradvancing the medical lead through the directing means wherein theadvancing means includes means for removably fixedly engaging thedirecting means and means for removably fixedly engaging the medicallead.
 17. The system of claim 16 wherein the directing means includes acentral axis and further includes means for directing the medical leadoutward from a distal end of the directing means away from the centralaxis.
 18. The system of claim 16 wherein the advancing means includes afixable member having means for removably fixedly engaging the directingmeans, and a movable member adapted to move laterally with respect tothe fixable member and having means for removably fixedly engaging thelead.
 19. The system of claim 18 wherein the movable member is adaptedto move laterally with respect to the fixable member upon rotation ofthe movable member.
 20. The system of claim 16 further including meansfor transferring torque to the lead, the torque transferring meansincluding means for interlockingly engaging the advancing means andmeans for removably fixedly engaging the lead.
 21. The system of claim20 wherein the lead includes a lumen and the torque transferring meansincludes a stylet insertable within the lead lumen.
 22. The system ofclaim 20 wherein the torque transferring means includes means forreceiving and retaining the proximal lead end.
 23. The system of claim20 wherein the torque transferring means includes a first interlockingmember and the advancing means includes a second interlocking memberadapted to interlockingly engage the first interlocking member.
 24. Thesystem of claim 16 wherein the directing means further includes meansfor administering a fluid.